It is possible to make a contribution to keeping pollutant emissions during operation of an internal combustion engine as low as possible by keeping low the pollutant emissions which are produced during the combustion of the air/fuel mixture in the respective cylinders. On the other hand, exhaust gas after-treatment systems which convert the pollutant emissions which are generated in the respective cylinder during the combustion process of the air/fuel mixture into harmless substances are used in internal combustion engines.
For this purpose, exhaust gas catalytic converters are used which convert carbon monoxide, hydrocarbons and, if appropriate, nitrogen oxides into harmless substances.
Both the selective influencing of the generation of the pollutant emissions during the combustion and the conversion of the pollutant components with a high level of efficiency by means of an exhaust gas catalytic converter require a very precisely set air/fuel ratio in the respective cylinder.
DE 10 2005 009 101 B3 discloses a cylinder-specific lambda control system, wherein a cylinder-specific air/fuel ratio deviation is determined, which is then fed to a closed-loop controller whose output variable is a closed-loop controller value for influencing the air/fuel ratio in the respective cylinder. The closed-loop controller comprises an integral component.
DE 10 2008 002 424 A1 discloses a method for operating an internal combustion engine in which a combustion feature is determined, and one or more application functions for the operation of the internal combustion engine are carried out as a function of the combustion feature.
DE 10 2010 012 140 A1 discloses a method for operating an internal combustion engine, wherein a lambda actual value and a lambda setpoint value of an exhaust gas are determined in an exhaust gas tract of the internal combustion engine, wherein an instantaneous setpoint value and an instantaneous actual value for a torque output by the internal combustion engine are determined, and wherein a charge is fed per work cycle to the working cylinders of the internal combustion engine via an air system. Furthermore, the instantaneous setpoint value is compared with the instantaneous actual value, wherein a difference between the lambda actual value and the lambda setpoint value is determined when a difference between the instantaneous setpoint value and the instantaneous actual value undershoots a predetermined threshold value. At least one operating parameter of the internal combustion engine, which influences the charge, is changed as a function of the difference between the lambda actual value and the lambda setpoint value in such a way that the difference between the lambda actual value and the lambda setpoint value is minimized.
DE 10 149 434 A1 discloses a method for controlling the torque of an internal combustion engine, having the following method steps: measuring the time profile of the pressure in the combustion chamber of at least one cylinder of the internal combustion engine; measuring the time profile of the rotational angle of the crankshaft of the internal combustion engine; calculating the indicated work and an internal torque from the pressure and the rotational angle of the internal combustion engine; and controlling the torque output by the internal combustion engine as a function of the internal torque.